The semiconductor substrate is manufactured by growing a semiconductor crystal in accordance with CZ method; forming a substrate from the semiconductor crystal; and heat treating the formed substrate at 1150.degree. C. or higher for 30 min or longer in non-oxidizing atmosphere (e.g., 1200.degree. C. for 1 hour in hydrogen gas). In the formed wafer, the density of bulk micro-defects is 5.times.10.sup.2 to 5.times.10.sup.6 pieces per cm.sup.-3 in the surface area, but 5.times.10.sup.7 pieces per cm.sup.-3 or more in an 20 .mu.m or deeper from the surface. To confirm the depth profile of BMD density, the substrate is further heat treated at 780.degree. C. for 3 hours in oxygen atmosphere and successively at 1000.degree. C. for 16 hours in oxygen atmosphere.